So...let's start with the beginning.
I entered in Sinnoh category.After i entered in Oreburgh City , i fighted with leader and I won.
All is ok...for now.
When i try to enter in Eterna City it didn't leave me.I fighted more in Oreburgh City with leader...and i try again to enter in Eterna.
It leaved me.I maked a battle with leader and i won.After that when i try again to enter in Veilstone City...it didn't leave me again.
I wait some time...and when i tryed to enter on Eterna it didn't leaved me again.
What's happening?
Please explain me.

So...let's start with the beginning.I entered in Sinnoh category.After i entered in Oreburgh City , i fighted with leader and I won.All is ok...for now.When i try to enter in Eterna City it didn't leave me.I fighted more in Oreburgh City with leader...and i try again to enter in Eterna.It leaved me.I maked a battle with leader and i won.After that when i try again to enter in Veilstone City...it didn't leave me again.I wait some time...and when i tryed to enter on Eterna it didn't leaved me again.What's happening?Please explain me.

After you fought Roark, did you do anything else besides going to Eterna City? If you just went to Eterna City right after fighting Roark, then it's a bug.

After you've won against Roark, do NOT go to the Pokemon Center, change your Battle team, OR Logout/Close the game tab/window. If you still can't battle him after that, it's a bug and you better contact Simon.

'Scuse me for gravedigging this post. But I'm having similar issues. So I'm not able to heal my pokemon after beating Roark? I have to beat the whole Sinnoh Region without healing? -Impossible, I've tried it so many times, could someone please help me out, I'd love to get the rest of my badges!

'Scuse me for gravedigging this post. But I'm having similar issues. So I'm not able to heal my pokemon after beating Roark? I have to beat the whole Sinnoh Region without healing? -Impossible, I've tried it so many times, could someone please help me out, I'd love to get the rest of my badges!

Well, it's the same with everyone else. They've managed to get it, so it's not impossible. Train hard and we know you can do it!

'Scuse me for gravedigging this post. But I'm having similar issues. So I'm not able to heal my pokemon after beating Roark? I have to beat the whole Sinnoh Region without healing? -Impossible, I've tried it so many times, could someone please help me out, I'd love to get the rest of my badges!

Yes, it clearly states that you cannot heal your Pokemon while fighting any Sinnoh leaders. It's definitely not impossible. I easily managed to beat them all without using Slakings. If you can't, then that's a sign that your Pokemon aren't good.

If you really want the easy way, then you can fight one leader and make a tab to the Pokemon Center after beating them while still on the battle page. Don't heal yet, and just go on to the next gym leader. On the next gym leader, just click on them, but don't fight them yet. Go to the tab with the Pokemon Center and heal. Then fight the gym leader and now your Pokemon are healed and you now have a crutch.

You have to beat all the gym leaders in sinnoh, without using heal center, many try to cheat by opening a new window and heal before the battle, but that doesn't work. You could buy some potions instead....

Without cheating, all you can do is train a powerful team to 100 and get a good moveset for them(more pp recommended). Also attach some items to boost their stats. And you can use potions and others. Most people have cheated. I have beaten it with a level 60-70 team. You might be surprised but all you need is a brain:)

Uh... I mean that I can beat the Sinnoh leaders without relying on crutches like Slaking? I cannot see how it's hard to understand that. Also, please don't make necro posts; your reply could had easily been sent on a PM.